SA Liberal MP Corey Wingard is not normally known for his quirky turn of phrase, but today produced a peculiar pearler to express scorn over delays to an Adelaide rail project — likening it to his nana's nightie.

The SA Government earlier said that electrification work would finally get underway within weeks on the Gawler train line, which is Adelaide's most used suburban railway and runs through the northern suburbs.

Mr Wingard seemed almost surprised at his own utterance, and added a more straight-faced remark about the likely impact on northern suburbs commuters.

"South Australians have been disappointed right across the board and in the north in particular they've been let down," he said.

Despite the momentary levity, the project will have significant consequences — the Government has shrewdly delayed major disruptions on the line until after the March election, as it seeks to avoid more flak from angry passengers.

"I don't think there's any planned interruption as a result of this Gawler electrification project until the October school holidays. Certainly we'll have more to say about that around the middle of the year," Transport Minister Stephen Mullighan said.

"We anticipate this being a construction schedule which will reach out to the middle of 2020, so a bit over two years."

Stage one of the $615 million project will electrify about half the line from Adelaide to Salisbury and will include installation of the overhead wiring, gantries and a new signalling system.

Construction firm Lendlease was awarded the contract to carry out the works, and the company estimates more than 135 jobs will be created.

"We've got a plan to minimise the disruption to the community and we've got the expertise to do the job really well," Lendlease project director Danny Parkinson said.

Mr Mullighan conceded the project "has had a chequered history" but blamed some of the delays on the Federal Government not committing funds.

"We'd love to [electrify] all of the way out to Gawler," he said.

"We've got our request in to the Federal Government, we've submitted our third business case to Infrastructure Australia so they can partner in this important public transport project."